@Eric – I suspect the most likely cause is that you’re using R2024b in which the memory model is different from the one used in 2014 when I wrote the original article (over 10 years and ~25 Matlab releases ago!). On R2018a or newer you should avoid using the mxGetPr() method, or at the very least mex-compile using the -R2017b flag. See https://www.mathworks.com/help/matlab/apiref/mxgetpr.html and https://undocumentedmatlab.com/articles/multi-threaded-mex for details. Using a bad reference pointer returned by mxGetPr() may well crash the program.

Possible other causes:
1) You’re using a pre-compiled version of the program that was compiled on another computer that has a non-100%-compatible compiler, or perhaps a different version of Matlab or libmex.dll in the compiled vs. run-time computers.
2) You did not trap your code in a try-catch block. The code calls mexErrMsgIdAndTxt() and this raises an exception that crashes your program since the exception is apparently uncaught. Take a look at the myPosixThread.c source code.
3) Perhaps in R2024b the interface of the mexErrMsgIdAndTxt() MEX function has changed since the time that I wrote the article in 2014. Check your local mex.h file.

Unhandled C++ exception detected at 2025-06-05 11:32:12 -0700

% Configuration:
% Crash Decoding : Disabled - No sandbox or build area path
% Crash Mode : continue (default)
% Default Encoding : UTF-8
% Deployed : false
% Graphics Driver : Uninitialized hardware
% Graphics card 1 : NVIDIA ( 0x10de ) NVIDIA RTX 2000 Ada Generation Version 32.0.15.5612 (2024-6-25)
% Graphics card 2 : Microsoft ( 0x0 ) Microsoft Remote Display Adapter Version 10.0.19041.5794 (2006-6-21)
% Java Version : Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
% MATLAB Architecture : win64
% MATLAB Entitlement ID : 98xxxxx
% MATLAB Root : C:\Program Files\MATLAB\R2024b
% MATLAB Version : 24.2.0.2773142 (R2024b) Update 2
% OpenGL : hardware
% Operating System : Microsoft Windows 10 Enterprise
% Process ID : 14612
% Processor ID : x86 Family 25 Model 24 Stepping 1, AuthenticAMD
% Session Key : 1b61df14-e0d5-49bd-9d0c-9157xxxxxx
% Window System : Version 10.0 (Build 19045)
%
% Fault Count: 1
%
% Abnormal termination:
% Unhandled C++ exception
%
% Current Thread: '' id 29128
%
% Register State (from fault):
% RAX = 0000000000000000 RBX = 00007ff936a6b468
% RCX = 0000000000000000 RDX = 0000000000000000
% RSP = 00000070073fd7f0 RBP = 00000070073ffad9
% RSI = 00000070073fd998 RDI = 0000000019930520
%
% R8 = 0000000000000000 R9 = 0000000000000000
% R10 = 0000000000000000 R11 = 0000000000000000
% R12 = 0000000000000000 R13 = 0000000000000000
% R14 = 0000000000000000 R15 = 0000000000000000
%
% RIP = 00007ff9d743af29 EFL = 00000206
%
% CS = 0033 FS = 0053 GS = 002b
%
% Stack Trace (from fault):
% [ 0] 0x00007ff9d743af29 C:\WINDOWS\System32\KERNELBASE.dll+00241449 RaiseException+00000105
% [ 1] 0x00007ff9ce896720 C:\Program Files\MATLAB\R2024b\bin\win64\VCRUNTIME140.dll+00026400 CxxThrowException+00000144
% [ 2] 0x00007ff9369f529c C:\Program Files\MATLAB\R2024b\bin\win64\libmex.dll+00545436 mexErrMsgIdAndTxt_800+00000220
% [ 3] 0x00007ff8f8c0112c C:\Users\Eric\Documents\MATLAB\PODs\myPosixThread.mexw64+00004396 mexFunction+00000300
% [ 4] 0x00007ff8f8be65bc C:\Program Files\MATLAB\R2024b\bin\win64\pthreadVC2.dll+00026044 pthread_key_delete+00020828
% [ 5] 0x00007ff9d7751bb2 C:\WINDOWS\System32\ucrtbase.dll+00138162 configthreadlocale+00000146
% [ 6] 0x00007ff9d98a7374 C:\WINDOWS\System32\KERNEL32.DLL+00095092 BaseThreadInitThunk+00000020
% [ 7] 0x00007ff9d9c3cc91 C:\WINDOWS\SYSTEM32\ntdll.dll+00314513 RtlUserThreadStart+00000033


@Shahbaz – I believe that your Matlab installation is corrupt. Try to uninstall Matlab and then re-install it from scratch.

@Oliver – Matlab does not include the Boost header files, but it is easy to view the documentation and download the relevant files from the Boost website. Be careful to download the version that fits your Matlab’s pre-installed version, otherwise segmentation violations could occur. For example, on R2014a Windows, the Boost threading library file is called boost_thread-vc100-mt-1_49.dll, indicating version 1.49 dated Feb 2012, two years behind the latest Boost release (change-log). It is not advisable in this case to install a newer Boost and link our MEX file with it, since clashes might occur with the standard Matlab libraries that use the older (pre-installed) Boost libs and are used internally by MEX.

For a working example, Kevin Stone’s SharedMemory utilities, use the Boost IPC library.

AbsurdlyCertain provides a detailed account of integrating Boost threads into MEX. Also see related here and here.

Boost certainly deserves a dedicated article. Care to take up my leads above and create a guest article here?